Well swab

ABSTRACT

A well swab and more particularly a well swab having an improved arrangement of reinforcing members therein including inner and outer concentric rows of circumferentially spaced reinforcing members with the reinforcing members of the inner and outer rows being spaced such that there is no overlapping therebetween and further that the reinforcing members have upper portions thereof which extend axially upwardly from the swab cup body member.

Umted States Patent [151 3,677,143 Crickmer 1 July 18, 1972 s41 WELLSWAB 2,912,291 11/1959 Moore ..92/241 [72] Inventor: Ch I D Cm 2923Memorial 3,448,987 6/1969 Stowe ..277/181 Dnve Houston 77024 PrimaryExaminer-Martin P. Schwadron [22] Filed: June 26, 1970 AssistantExaminer-Irwin C. Cohen pp No 50 118 Attorney-Howard E. Sandler [57]ABSTRACT A we" swab and more a wab having an improved arrangement ofreinforcing members therein including [58] Field Search igf {g i innerand outer concentric rows of circumferentially spaced reinforcingmembers with the reinforcing members of the inner and outer rows beingspaced such that there is no over- [56] Rem-"Ices Cited lappingtherebetween and further that the reinforcing mem- UNITED STATES PATENTSbets have upper portions thereof which extend axially upward] from theswab cu bod member. 2,723,721 11/1955 Corsette ..l66/202 X y p y2,887,347 5/1959 Losey ..92/241 9 Claims, 4 Drawing Figures PATENTEUJUL! 81972 INVENTOI? CHARL 5 D CR/CKMFR A Home y FIG. I

WELL SWAB Well swab assemblies of a type used in oil and gas wells arelowered into a tubing to a predetermined depth and rapidly liftedupwardly therethrough to clean out drilling mud from an oil well tubing,unload water from a gas well and the like. Such swab assembliesgenerally have a plurality of spaced flexible swab cups positioned aboutthe outer periphery thereof. As the swab assembly is lifted upwardly theswab cups expand radially outwardly to form a fluid tight seal betweenthe swab assembly and the inner periphery of the tubing thereby enablingthe unloading of drilling mud and the like from the tubing.

In a swabing operation the swab cups are subjected to pressures on theorder of several thousand pounds per square inch and as such the designthereof must produce cups having sufficient strength to withstand suchpressures while maintaining flexibility to enable the cups to passthrough the tubing in sealing engagement therewith.

Various cup reinforcing means have been used in an attempt to design aswab cup having sufficient strength and flexibility, such meansincluding: a row of reinforcing bars concentrically positioned inwardlyadjacent the outer periphery of the swab cup, such bars being spacedfrom one another or touching; and a continuous panel reinforcingpositioned inwardly adjacent the outer periphery of the swab cup.Practice has shown the reinforcing means comprising touching bars orcontinuous panels resulted in swab cups which lacked sufficientflexibility to contract when passing through pipe ends, necked downportions of pipe, out of round or dented pipe and the like.Additionally, the continuous panel type reinforcing is expensive tofabricate and is more susceptible to fatigue failure. The reinforcingmeans comprising the spaced bars has been found to be adequate insofaras initial strength and flexibility requirements, however, rubber feedwear during swabbing operation causes premature blowout failure betweenthe bars.

By means of the present invention, which includes a swab cup havinginner and outer rows of circumferentially spaced reinforcing bars, theinner bars being alternately spaced with respect to the outer bars, thestrength and flexibility requirements of the swab cup are accomplishedwhile substantially reducing the rubber feed between the outerreinforcing bars.

These and other objects and advantages of this invention will becomemore readily apparent from a reading of the following description anddrawings, in which:

FIG. 1 is a side view, partly in section, of a well swab assemblyprovided with swab cups embodying the principles of this invention;

FIG. 2 is a perspective view, partly in section of a swab cup of thisinvention;

FIG. 3 is a cross sectional view of a swab cup taken on lines Ill-III ofFIG. 2;

FIG. 4 is a cross sectional view of a swab cup taken on lines lV-IV ofFIG. 2;

FIG. Sis a portion of a cross sectional view similar to FIG. 3 showingan alternative form of a swab cup embodying the principles of thepresent invention; and

FIG. 6 is a cross sectional view of an alternative form of a reinforcingmember utilized in a swab cup embodying the principles of the presentinvention.

A well swab assembly 10 (FIG. 1) shown within a well casing or tubing 22includes a hollow tubular mandrel 12 having a valve cage 14 and a nosepiece 16 releasably secured thereto at the upper and lower ends thereof,respectively. Valve cage 14 has the upper end thereof releasably securedto suitable means (not shown) for moving the well swab assembly 10through a well tubing 22. A suitable ball valve 20 is movably disposedwithin cage 14 such that when assembly 10 is descending into the welltubing 22, drilling fluid within tubing 22 downwardly of assembly 10flows: through a plurality of portals 24 in nose piece 16 which portals24 communicate between tubing 22 and the inner periphery of swabassembly 10; through mandrel 12 whereat valve 20 is moved upwardly fromthe normal seated position thereof, such normal seated position closesoh the mandrel 12 at the upper end thereof; and through a plurality ofportals 26 in cage 24 wherefrom the fluid discharges from assembly 10into tubing 22 adjacent the upper end of assembly 10.

A plurality of swab cup assemblies, as shown two swab cup assemblies 28,are disposed about mandrel l2 and held in spaced relationship to oneanother and to the valve cage 14 by means of spacer sleeves 30. Thelowermost swab cup assembly 28 has the lowermost end thereof in contactwith the uppermost end of nose piece 16. Mandrel 12 can be provided withsuitable shoulder portions (not shown) adjacent swab cup assemblies 28and valve cage 14 and if such shoulder portions are provided, spacersleeves 30 would not be required.

Each assembly 28 includes an annular bowl or thimble member 32 at thelower end thereof constructed of steel or the like and a resilienttubular body or swab cup 34 formed of any suitable elastomeric typematerial, such as rubber or plastic which possess physical properties oftensile, elongation, hardness and the like of well known values in theswab cup art. The lower end of swab cup 34 engages thimble member 32 andextends upwardly therefrom.

As the well swab assembly 10 starts to ascend, the pressure of the wellfluid upwardly of the swab cups 34 urges the upper free ends thereofradially outwardly into frictional sealing engagement with the walls oftubing 22. The weight of the fluid upwardly of the ascending assembly 10subjects the swab cups 34 to relatively high stresses often in the orderof several thousand pounds per square inch and as such the cups musthave sufficient strength to withstand such pressures while maintainingsufiicient flexibility to enable the cups 34 to deform radiallyoutwardly into sealing engagement with the walls of tubing 22 asdescribed hereinabove. To obtain such strength while maintaining thenecessary flexibility the swab cups 34 are provided with the reinforcingmeans of this invention, which reinforcing means include inner and outerrows of concentrically arranged reinforcing bars, such bars beingindicated at 42 and 44 respectively. The reinforcing bars in each roware spaced circumferentially such that bars 42 and 44 are staggered withrespect to one another. The staggering of bars 42 and 44 is necessaryfor as well swab assembly 10 is ascending, the elastomer of the swabcups 34 intermediate adjacent outer bars 44 has a tendency to extrudeoutwardly thereby resulting in excessive swab cup wear in such extrudingareas which causes blow out and premature swab cup failure. Theinclusion of an inner bar 42 intermediate adjacent outer bars 44 reducesthe amount of extrusion during the ascending of assembly 10 and as suchincreases the life of a swab cup 34. Bars 42 and 44, sleeve 30, thimblemember 32, and swab cup 34 may be molded in one operation into a unitaryswab cup assembly 28. Since the swab cup 34 is formed of a resilientelastomeric material, the upper portion thereof is free to flex inwardlyand outwardly and accordingly the reinforcing bars 42 and 44 move asrequired to accommodate such flexing movement.

Swab cup 34 comprises: an elongated hollow tubular main body portion 36;a lip portion 38 extending upwardly from the upper end of main bodyportion 36 which, as shown, has an outer diameter thereof approximatelyequal to the outer diameter of portion 36 and a lower inside peripheralsurface 37 or portion 38 which tapers upwardly, radially outwardly fromthe inner periphery of portion 36 to a point intermediate the inner andouter diameter of portion 36 whereat an upper inside peripheral surface39 of portion 38 progresses upwardly at a substantially constant innerdiameter; and a plurality of circumferentially spaced finger portions 40which extend upwardly from lip portion 38. The outer periphery of fingerportions 38 taper radially inwardly from the lowermost ends thereof.Outer reinforcing bars 44 are circumferentially spaced radially inwardlyadjacent the outer periphery of portion 36. The lower ends ofreinforcing bars 44 can be supported in any suitable manner for example,as shown, such lower ends are received within thimble member 32 oralternatively, such lower ends can be encapsulated by portion 36 duringthe molding thereof such that support therefor is by the elastomericmaterial of portion 36 only. The upper ends of bars 44 are respectivelyencased within finger portions 38 and taper radially inwardly, as shownsuch taper being in a plane substantially parallel to the taper ofrespective finger portions 40. The radially inward tapering of fingerportions 40 and bars 44 at the upper ends thereof reduces theprobability of a well swab assembly being fouled on necked down or outof round or dented portions of well tubing 22 during a swabbingoperation.

lnner reinforcing bars 42 have the lower ends thereof sup ported in amanner hereinabove described with reference to bars 44 and extendupwardly therefrom in a plane substantially parallel to the longitudinalaxis of assembly 28. A lower portion 46 of bars 42 is encased withinbody portion 34 outwardly adjacent the inner periphery thereof. An upperportion 48 of bars 42, which portion 48 is not encased by swab cup 34,extends through peripheral surface 37 and has the uppermost end thereofspaced upwardly from the upper end of lip portion 38.

The above described arrangement of reinforcing bars 42 provides anefficient and relatively long term use of a swab cup 34 for experiencehas shown that the elastomeric material, intermediate adjacent bars 44and spaced downwardly from the upper ends of lip portion 38, wears awayrapidly during swabbing operations. Accordingly, if the uppermost endsof bars 42 were encased by elastomeric material and had the uppermostextent thereof below the upper end of lip portion 38, the bars 42 wouldhave a tendency to move radially outward between adjacent bars 44 wherethe elastomeric material was worn away and possibly catch on necked downor dented or out of round portions of the tubing 22 during the swabbingoperation. By providing for an arrangement where portion 48 extendsupwardly of lip portion 38 the above described tendency of bars 42 tomove radially outward between bars 44 of the worn intermediate sectionsof elastomeric material is greatly reduced.

The significant features of this invention include: the staggeredarrangement of inner and outer rows of spaced reinforcing bars within aswab cup which staggered arrangement reduces rubber feed betweenadjacent outer reinforcing bars while still maintaining required swabcup flexibility; and the arrangement whereby the inner row ofreinforcing bars have the upper portions extending upwardly from themain body portion 36. Accordingly, by following the principles taught bythis invention one skilled in the art can achieve the hereinabovementioned features with alterations to the preferred embodimenthereinabove described, for example: the upper radially inward taperingportions of bars 44 can be free of encasing elastomeric material, thatis, swab cup assembly 28 can be constructed without finger portions 40or; the upper radially inward tapering portions of bars 44 can beencased by an elastomeric flash rather than the molded finger portions40; portion 48 of bars 42 can be encased by an elastomeric flash ormolded finger portions which extend upwardly from main body portion 36;reinforcing bars 42 and 44 can be of any suitable cross section, forexample, circular, triangular or square and such bars need not have thesame cross section in a given swab cup assembly; lip portion 38 need nothave the tapering surface 37 but rather can be of a constant innerdiameter throughout the length thereof; and a well known tube shapedmember can be provided adjacent the inner diameter of body portion 36and at a lower end portion thereof for additional reinforcing ifrequired.

Some of the alternatives discussed hereinabove are shown in FIGS. 5 and6. FIG. 5 is a portion of a cross sectional view similar to FIG. 3 andshowing an alternative form of a swab cup with the primary distinctionbetween FIG. 5 and FIG. 3 being that the upper radially inward taperingportion of bars 44 are encased by a thin elastomeric coating or flashand portion 48 of bars 42 are encased by molded finger portions whichextend upwardly from the main body portion 36. FIG. 6 Illustrates a bar44' having a generally triangular rather than a circular cross section.

The description herein does not limit the structureof this invention andthe invention is defined by the scope of the claims hereinafter.

What is claimed is:

1. A swab cup comprising: an axially elongated flexible elastomericgenerally annular body member; reinforcing means including inner andouter concentric rows of circumferentially spaced reinforcing memberswhich extend generally axially of said body member; said outer row beingradially inwardly adjacent the outer periphery of said body member; saidinner row being radially outwardly adjacent the inner periphery of saidbody member; the reinforcing members of said inner row being spacedcircumferentially with respect to adjacent reinforcing members of saidouter row with no overlapping therebetween; and said reinforcing membersof said inner row having upper portions thereof which extend generallyaxially upwardly from the uppermost end of said body member.

2. A swab cup as specified in claim 1 wherein said reinforcing membersof said outer row have upper portions thereof which extend generallyaxially upwardly from said uppermost end of said body member.

3. A swab cup as specified in claim 2 wherein said upper portions ofsaid reinforcing bars of said outer row taper radially inwardly fromsaid uppermost end of said body member, the uppermost ends of said upperportions of said reinforcing members of said outer row being spacedradially outwardly from the inner periphery of said body member.

4. A swab cup as specified in claim 3 wherein said upper portions ofsaid reinforcing members of said outer row are respectively encapsulatedby circurnferentially spaced up wardly extending elastomeric fingerportions.

5. A swab cup as specified in claim 3 wherein said upper portion of saidreinforcing members of said outer row are encapsulated by a thinelastomeric coating.

6. A swab cup as specified in claim 1 wherein said upper portions ofsaid reinforcing members of said inner row are encapsulated bycircumferentially spaced upwardly extending elastomeric finger portions.

7. A swab cup as specified in claim 1 wherein said upper portions ofsaid reinforcing members of said inner row are encapsulated by a thinelastomeric coating.

8. A swab cup as specified in claim 1 wherein said reinforcing membershave a circular cross section.

9. A swab cup as specified in claim 1 wherein at least some of saidreinforcing members have a polygonal cross section.

1. A swab cup comprising: an axially elongated flexible elastomericgenerally annular body member; reinforcing means including inner andouter concentric rows of circumferentially spaced reinforcing memberswhich extend generally axially of said body member; said outer row beingradially inwardly adjacent the outer periphery of said body member; saidinner row being radially outwardly adjacent the inner periphery of saidbody member; the reinforcing members of said inner row being spacedcircumferentially with respect to adjacent reinforcing members of saidouter row with no overlapping therebetween; and said reinforcing membersof said inner row having upper portions thereof which extend generallyaxially upwardly from the uppermost end of said body member.
 2. A swabcup as specified in claim 1 wherein said reinforcing members of saidouter row have upper portions thereof which extend generally axiallyupwardly from said uppermost end of said body member.
 3. A swab cup asspecified in claim 2 wherein said upper portions of said reinforcingbars of said outer row taper radially inwardly from said uppermost endof said body member, the uppermost ends of said upper portions of saidreinforcing members of said outer row being spaced radially outwardlyfrom the inner periphery of said body member.
 4. A swab cup as specifiedin claim 3 wherein said upper portions of said reinforcing members ofsaid outer row are respectively encapsulated by circumferentially spacedupwardly extending elastomeric finger portions.
 5. A swab cup asspecified in claim 3 wherein said upper portion of said reinforcingmembers of said outer row are encapsulated by a thin elastomericcoating.
 6. A swab cup as specified in claim 1 wherein said upperportions of said reinforcing members of said inner row are encapsulatedby circumferentially spaced upwardly extending elastomeric fingerportions.
 7. A swab cup as specified in claim 1 wherein said upperportions of said reinforcing members of said inner row are encapsulatedby a thin elastomeric coating.
 8. A swab cup as specified in claim 1wherein said reinforcing members have a circular cross section.
 9. Aswab cup as specified in claim 1 wherein at least some of saidreinforcing members have a polygonal cross section.